Labeling apparatus of this type is designed to transfer self-adhesive labels onto a continuously fed series of products or continuosly fed packaging material. The labels are fed on a carrier belt laterally toward the flow path of the products or their packaging, are pulled off the carrier belt via an acute angled pull-off edge, transferred to a conveyor belt extending transversely to the product flow path, removed from the conveyor belt and impressed on the products.
The timing of the delivery of the labels at the pull-off edge and thus of the transfer to the conveyor belt can be predetermined by suitable control of the drive of the label carrier belt. To the extent that, as is frequently the case, several products are simultaneously fed side-by-side on the material flow path, and thus several labels must be transferred at distances one after another upon the conveyor belt, control of the positions and the spacings between the labels on the conveyor belt is effected by means of a program which takes into account the spacing of the products and the speed of the transport belt, and which can control the movement of the carrier belt and thus the delivery of the labels. The production of such a program requires a series of complex calculations and presupposes precise maintenance of all velocities of movement. Corrections of the positions of labels relative to the products or their containers are thus possible during operation at most to the extent that the timing of delivery for all the labels is moved ahead or back, or the distance between all labels is altered to the same degree. Any other changes require the use of totally new programs.
However, in practise it is frequently necessary or at least desirable to fine-tune the positions of the labels for each of the product rows arriving side by side, either because the products may be arriving with different spacings or orientations, or because labeling at different locations on the products may be required, or for other reasons.